sensors & systems - Industrial Technology Magazine

dealing
with all the
pressure
you need
fans and blowers for extraction, cooling,
ventilation, aeration, vacuum and drying
• Backward curved bladed single inlet
centrifugal blowers
• Flow rates up to 850m 3 /hr (500CFM)
• Pressures upto 150mBar (60in.SWG)
• Exceptionally low noise levels
• Reliable and maintenance free
• ATEX versions
• Many configurations and add-ons
ACI’s Multi Stage Range of directly driven blowers offers
exceptionally quiet running and maintenance free
solutions for many higher pressure applications.
Direct mounting of the impellers and low motor speeds minimise
noise levels whilst providing high pressure performance. The Multi
Stage’s modular system design gives a flexible choice in the number
of stages combined. Power supply options available.
Please contact us for further detailed specifications and to
discuss suitability for your application.
www.aircontrolindustries.com
the solution providers for air movement problems
Air Control Industries Ltd
Silver Street,
T: +44(0)845 5000 501
Chard,
F: +44(0)845 5000 502
Somerset,TA20 2AE, UK E: sales@aircontrolindustries.com
ELECTRICAL EQUIPMENT & DESIGN
Time to check
your cable
glands?
Terry Spriggs of Hylec Components helps
to keep your knowledge up-to-date by
giving an overview of what has changed
and what is now available
There are now more
variations of cable gland
available than ever, and with
more choice comes the
requirement for more knowledge in
order to make the right selection.
Considerations such as suitability for
purpose, sealing, safety and
installation time all need to be
balanced against cost, which is
always an issue.
It is as easy to overlook a cable
gland as it is to under-specify or to
over-specify it. With a huge range of
fast new push-fit designs, tighter
regulations and new materials
coming onto the market it is essential
to look at what is fit-for-purpose.
Essential criteria include the quality
of the hole available for the cable
entry, the thickness of the cable, the
ingress protection required, the
mechanical cable retention strength
required, and the environment it is
being exposed to. Exposure to heat,
weathering and any fire requirements
such as building regulations, halogen
free requirements, Ex rating or ATEX
zones have to be considered.
One of the original and simplest
types of cable gland is the ‘stuffing
gland’ offering basic sealing and
protection for cables passing through
panels or bulkheads. A locking nut is
used to apply pressure via a skid
washer onto the sealing rings that
spread to form a seal around the
cable. This method of cable feedthrough
achieves three basic
functions. It protects the cable from
possible damage due to any sharp
edges on the bulkhead/wall/cabinet.
It provides a barrier to moisture and
debris entering the equipment
housing (IP ratings are generally low
as they will not withstand
pressurised water or immersion). And
it provides a measure of cable
retention. The stuffing gland has
been around for many years and is
used in an enormous number of
applications today. However, a major
problem with these particular types
of traditional gland is the limited
mechanical performance and its
protection rating of IP54.
Many applications require better
cable retention, in terms of factors
like superior mechanical strength, a
wider clamping range and a higher
rating of IP65, or IP68 (which can be
buried and/or kept under full
emersion in water). These needs are
catered for by a dome topped cable
gland. These glands are also more
aesthetically pleasing, looking more
modern and smartening up an
installation. A number of variations of
this type are available in both Nylon
and metal but the salient features
that ensure superior performance to
the traditional stuffing gland are in its
construction.
The cable is again fed through a
sealing ring but in this case, the
sealing ring is placed within an 'iris'
that closes onto the sealing ring,
clamping the cable and forming a
high IP seal as the dome top is
screwed down.
Dome top variations
Many different cable gland variations
exist in dome top configurations
covering a variety of general
industrial applications. Specialist
applications may require additional
protection over and above the
common plastic variations. There
are, for example, products designed
to meet the requirement of ATEX
100a for hazardous areas such as
petrochemical. And there are glands
designed for EMC compatibility and
certified by VDE in compliance with
VG 95373 part 40. Stainless steel
versions should be considered in food
and chemical process applications
28 More details: Write in 280 on the free information card
INDUSTRIAL TECHNOLOGY • May 2008